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IJCBS, 1(2012):36-47
International Journal of Chemical and Biochemical Sciences
Journal Home page: www.iscientific.org/Journal.html
© International Scientific Organization
Food: Its preservatives, additives and applications
Hamid A. Abdulmumeen1*, Ahmed N. Risikat2 and Agboola R. Sururah1
1
Department of Chemistry, University of Ilorin, P.M.B. 1515, Ilorin-Nigeria
2Department of Microbiology, University of Ilorin, P.M.B. 1515, Ilorin-Nigeria
Abstract
Foods are substances or mixture of substances both solid and/or liquid, which are intended for human consumption or
ingestion for their nutritional of pleasurable benefits. The classification of food, its storage and chemistry were treated in this
study. Different methods of food preservations which include drying (spray drying, freeze drying), freezing, vacuum-packing,
canning, sugar crystallization, pickling, food irradiation, etc. and its effect were also reviewed. Further, Food additives and its
effect, and significance of food preservatives and additives were also explained in this review.
Keywords: preservatives, additives, vacuum-packing, spray drying, Monosodium Glutamate, tartrazine.
Review article Received: 08-11-2011 Revised: 14-12-2011 Accepted: 16-12-2011 Available online: 15-01-2012
*Corresponding Author, e-mail: hamidmemo@yahoo.com; hamidmemo@gmail.com; hamid.aa@unilorin.edu.ng
1. Introduction is supplied by the food industry operated by multinational
corporations using intensive farming and industrial
Food is any substance or material eaten or drunk to agriculture methods. Almost all foods are of plant or animal
provide nutritional support for the body or for pleasure [1]. origin. Cereal grain is a staple food that provides more food
It usually consists of plant or animal origin, which contains energy worldwide than any other type of crop. Maize, wheat
essential nutrients, such as carbohydrates, fats, proteins, and rice together account for 87% of all grain production
vitamins, or minerals, and is ingested and assimilated by an worldwide. Other foods not from animal or plant sources
organism to produce energy, stimulate growth and maintain include various edible fungi, especially mushrooms: Fungi
life. Food chemistry is the study of chemical processes and and ambient bacteria are used in the preparation of
interactions of all biological and non-biological components fermented and pickled foods such as leavened bread,
of foods. The biological substances include meat, poultry, alcoholic drinks, cheese, pickles, kombucha and yoghurt,
lettuce, beer, and milk as examples. It is similar to Blue-green algae such as Spirulina. Inorganic substances,
biochemistry in its main components such as carbohydrates, baking soda, cream of tartar are also used to chemically alter
lipids, and protein, but it also includes areas such as water, an ingredient [2].
vitamins, minerals, enzymes, food additives, flavors, and Many plants or plant parts are eaten as food. There
colors. This discipline also encompasses how products are around 2,000 plant species which are cultivated for food,
change under certain food processing techniques and ways and many have several distinct cultivars. Seeds of plants are
either to enhance or to prevent them from happening. An good sources of food for animals, including humans because
example of enhancing a process would be to encourage they contain nutrients necessary for the plant’s initial
fermentation of dairy products with microorganisms that growth, including many healthy fats, such as Omega fats. In
convert lactose to lactic acid; an example of preventing a fact, the majority of foods consumed by human beings are
process would be stopping the browning on the surface of seed-based foods. Edible seeds include cereals (such as
freshly cut Red Delicious apples using lemon juice or other maize, wheat, and rice), legumes (such as beans, peas, and
acidulated water [1]. lentils), and nuts. Oilseeds are often pressed to produce rich
oils, such as sunflower, flaxseed, rapeseed (including canola
2. Food and its Classification oil), and sesame [2]. One of the earliest food recipes made
from ground chickpeas is called hummus, which can be
Historically, people obtained food from hunting, traced back to Ancient Egypt times. Seeds are typically high
farming, ranching, and fishing, known as agriculture. Today, in unsaturated fats and, in moderation, are considered a
most of the food energy consumed by the world population healthy food, although not all seeds are edible. Large seeds,
36
Abdulmumeen et al., 2012
IJCBS, 1(2012):36-47
such as those from a lemon pose a choking hazard, whereas history, agriculture can be described as organic; only during
seeds from apples and cherries contain poison cyanide. the 20th century was a large supply of new synthetic
Fruits are the ripened ovaries of plants, including the seeds chemicals introduced to the food supply. This more recent
within. Many plants have evolved fruits that are attractive as style of production is referred to as “conventional.” Under
a food source to animals, so that animals will eat the fruits organic production, the use of conventional non-organic
and excrete the seeds some distance away. Fruits, therefore, pesticide (including insecticides, fungicides, and herbicides)
make up a significant part of the diets of most cultures. is precluded.
Some botanical fruits, such as tomatoes, pumpkins and
eggplants, are eaten as vegetables. Vegetables are second Food Storage is both a traditional domestic skill
types of plant matter that are commonly eaten as food. and is important industrially. Food is stored by almost every
These include root vegetables (such as potatoes and carrots), human society and by many animals. Storing of food has
leaf vegetables (such as spinach and lettuce), stem several main purposes: preparation for periods of scarcity or
vegetables (such as bamboo shoots and asparagus), and famine, taking advantage of short term surplus of food as at
inflorescence vegetables (such as globe artichokes and harvest time, enabling a better balanced diet throughout the
broccoli). Many herbs and spices are highly flavorsome year, preparing for special events and celebrations, planning
vegetables [2]. Other classifications of food are discussed for catastrophe or emergency, religious reasons (LDS
below: Church leaders council church members to store food) and
protection against predators or others [7].
Fast food is the term given to food that can be
prepared and served very quickly. While any meal with low Domestic food storage
preparation time can be considered to be fast food, typically
the term refers to food sold in a restaurant or stored with Grain: Grain is stored in a rigid, sealed container
preheated or precooked ingredients and served to the to prevent ingress of moisture or attack by vermin. Storage
customer in a packaged form for take-out/take-away. The in grain sacks is not effective. Mold and pests destroy a
term “fast food” was recognized in a dictionary by Merriam- 25kg cloth sack of grain in a year – even if stored off the
Webster (1951). Outlets may be stands or kiosks, which may ground in a dry area. On the ground or damp concrete, the
provide no shelter or seating [3] or fast food restaurants time is as little as three days, and the grain might have to be
(also known as quick service restaurants). Franchise dried before it can be milled. Food stored under unsuitable
operations which are part of restaurant chains have conditions should not be purchased or used because of risk
standardized foodstuffs shipped to each restaurant from of spoilage. To test whether grain is still good, sprout some.
central locations [4]. If it sprouts, it is still good, but if not, it should not be eaten.
It may take up to a weak for grains to sprout. When in
Junk food is an informal term applied to some doubt, throw it out.
foods which are perceived to have little or no nutritional
value, or to products with nutritional value but which also Meat: Unpreserved meat has only a relatively short
have ingredients considered unhealthy when regularly eaten, life in storage. Pork should be eaten within one day but beef
or to those considered unhealthy to consume at all. The term and venison improve with up to 5 days storage in a cold
was coined by Michael Jacobson, Director of the Center for room. Dry aging techniques are sometimes used to tenderize
Science in the Public Interest, in 1972 [5]. Junk foods are specialty gourmet meats by hanging them in carefully
typically ready to eat convenience foods containing high controlled environments for up to 21 days. Semi-dried meats
levels of saturated fats, salt, or sugar; and little or no fruit, like salamis and country style hams are processed first with
vegetables, or dietary fibre, and do not provide any health salt, smoke, sugar, or acid, or other “cures” then hung in
benefits. Junk food includes foods such as soft drinks, cool dry storage for extended periods, sometimes exceeding
hamburgers, hot dogs, ice cream, cake, French fries, a year.
chocolate, confectionery, pizza, cookies, fried chicken,
onion rings and doughnuts. Fish and shellfish: It is unsafe to store fish or
shellfish without preservation. Fresh shellfish and whitefish
Whole foods are foods that are unprocessed and should be eaten within a few hours of harvesting.
unrefined, or processed and refined as little as possible
before being consumed. Whole foods typically do not Use of stored food: Guidance for surviving
contain added ingredients, such as sugar, salt, or fat. emergency conditions in many parts of the world
Examples of whole foods include unpolished grains; fruits recommends maintaining a store of essential foods; typically
and vegetables; unprocessed meat, poultry, and fish; and water, cereals, oil, dried milk, and protein rich foods such as
non-homogenised milk. The term is often confused with beans, lentils, tinned fish and meat. A basic food storage
organic food, but whole foods are not necessarily organic, calculator can be used to help determine how much of these
nor are organic foods necessarily whole. Because of the lack staple foods a person would need to store in order to sustain
of basic processing, some whole foods have a very short life for one full year [8]. In addition to storing the basic food
shelf life [6]. items, many people choose to supplement their food storage
with frozen or preserved garden-grown fruits and vegetables
Organic foods are made in a way that complies and freeze-dried or canned produce. An unvarying diet of
with organic standards set by national governments and staples prepared in the same way can cause appetite
international organisations. For the vast majority of human exhaustion. An additional benefit to having a basic supply of
Abdulmumeen et al., 2012 37
IJCBS, 1(2012):36-47
food storage in the home is for the cost savings. Costs of dry people try to limit their intake of dietary fat to avoid
bulk foods (before preparation) are often considerably less becoming overweight. In most instances, fats are from
than convenience and fresh foods purchased at local markets animal products-meats, milk products, eggs, seafood and
or super-markets. If good food storage guidelines are oils are from plants-nuts, olives, and seeds. We use lipids for
followed, using and replenishing your food storage should flavor, to cook foods, and to improve the texture of foods.
become a commonplace, everyday activity, as normal as Proteins are important components of food. Every
preparing meals. Although it does require an initial cell requires protein for structure and function. Proteins are
investment to stock a pantry, eventually it becomes the most complex polymers composed of amino acids. There are 20
economical and convenient way to live. Instead of going to amino acids found in the body. Eight of these are essential
the store when you need something and paying full price for for adults and children, and nine are essential for infants.
it, you can go to your storage room or pantry to get what Essential means that we cannot synthesize them in large
you need. Then you replace it next time it is on sale. The enough quantities for growth and repair of our bodies, and
best way to rotate your food storage is to prepare meals with therefore, they must be included in our diet. Proteins consist
it on a daily basis. Of course, that means that you should of long chains of 100-500 amino acids that form into three-
store what your family will eat. It is wasteful to store dimensional structures, they native state. When you change
products that your family won’t eat or that can’t be used in the native state of the protein, you change the three-
your favorite recipes [9]. Grain and beans are stored in tall dimensional structure, which is referred to as denaturation.
grain elevators, almost always at a rail head near the point of Factors that cause denaturation include heating, acid,
production. The grain is shipped to a final user in hoper cars. beating and freezing [11].
In the former Soviet Union, where harvest was poorly
controlled, grain was often irradiated at the point of Preservation of Food is the process of treating and
production to suppress mold and insects. In the U.S., handling food to stop or greatly slow down spoilage (loss of
threshing and drying is performed in the field, and transport quality, edibility or nutritive value) caused or accelerated by
is nearly sterile and in large containers that effectively micro-organisms. Some methods, however, use benign
suppress pest access, so irradiation is not required. At any bacteria, yeasts or fungi to add specific qualities and to
given time, the U.S. usually has about two weeks of stored preserve food (e.g. cheese, wine). Maintaining or creating
grains. Fresh fruits and vegetables are either packed in nutritional value, texture and flavour is important in
plastic cups in cardboard boxes for fresh premium markets, preserving its value as food. This is culturally dependent, as
or placed in large plastic tubs for sauce and soup processors. what qualifies as food fit for humans in one culture may not
Fruits and vegetables are usually refrigerated at the earliest qualify in another culture. Preservation usually involves
possible moment, and even so have a shelf life of two weeks preventing the growth of bacteria, fungi, and other micro-
or less. organisms, as well as retarding the oxidation of fats which
cause rancidity. It also includes processes used to inhibit
3. Chemistry of Food natural ageing and discolouration that can occur during food
preparation such as the enzymatic browning reaction in
Food chemistry or chemistry is the study of apples after they are cut [12].
chemical processes and interactions of all biological and
non-biological components of foods [10]. It also deals with 4. Classification of Food preservation: Some preservation
the production, processing, distribution, preparation, methods require the food to be sealed after treatment to
evaluation, and utilization of food. Food chemists work with prevent recontamination with microbes; others, such as
plants that have been harvested for food, and animals that drying, allow food to be stored without any special
have been slaughtered for food. Food chemists are containment for long periods. Common methods of applying
concerned with how these food products are processed, these processes include drying, spray drying, freeze drying,
prepared, and distributed. For example, to address consumer freezing, vacuum-packing, canning, preserving in syrup,
demands, some food chemists are involved with finding fat sugar crystallization, food irradiation, and adding
and sugar substitutes that do not alter food taste and texture. preservatives or inert gases such as carbon dioxide. Other
Basic food chemistry deals with the three primary methods that not only help to preserve food, but also add
components in food: carbohydrates, lipids and proteins. flavour, include pickling, salting, smoking, preserving in
Carbohydrates make up a group of chemical syrup or alcohol, sugar crystallization and curing.
compounds found in plant and animal cells. They have an Preservation processes include:
empirical formula C H O or CH O. Since this formula is Heating to kill or denature micro-organisms (e.g.
n 2n n 2
essentially a combination of carbon and water these boiling)
materials are called “hydrates of carbon or carbohydrates”. Oxidation (e.g. use of sulfur dioxide)
Carbohydrates are the primary product of plant Toxic inhibition (e.g. smoking, use of carbon dioxide,
photosynthesis, and are consumed as fuel by plants and vinegar, alcohol etc)
animals. Food carbohydrates include the simple Dehydration (drying)
carbohydrates (sugars) and complex carbohydrates (starches Osmotic inhibition (e.g. use of syrups)
and fiber). Lipids include fats, oils, waxes, and cholesterol. Low temperature inactivation (e.g. freezing)
In the body, fat serves as a source of energy, a thermal Ultra high water pressure (e.g. fresherised, a kind of
insulator, and a cushion around organs; and it is an
important component of the cell. Since fats have 2.25 times “cold” pasteurization, the pressure kills naturally
the energy content of carbohydrates and proteins, most occurring pathogens, which cause food deterioration
and affect food safety). These methods include:
Abdulmumeen et al., 2012 38
IJCBS, 1(2012):36-47
i. Drying: One of the oldest methods of food preservation is vii. Lye: Sodium hydroxide (lye) makes food too alkaline for
by drying, which reduces water activity sufficiently to bacterial growth. Lye will saponify fats in the food, which
prevent or delay bacterial growth. Drying also reduces will change its flavour and texture. Lutefisk uses lye in its
weight. preparation, as do some olive recipes. Modern recipes for
century eggs also call for lye. Masa harina and hominy
ii. Freezing: Freezing is also one of the most commonly use agricultural lime in their preparation and this is often
used processes commercially and domestically for misheard as ‘lye’.
preserving a very wide range of food including prepared
food stuffs which would not have required freezing in viii. Canning and bottling: Canning involves cooking food,
their unprepared state. For example, potato waffles are sealing it in sterile cans or jars, and boiling the containers
stored in the freezer, but potatoes themselves require only to kill or weaken any remaining bacteria as a form of
a cool dark place to ensure many months’ storage. Cold sterilization. It was invented by Nicolas Appert [11].
stores provide large volume, long-term storage for Foods have varying degrees of natural protection against
strategic food stocks held in case of national emergency in spoilage and may require that the final step occur in a
many countries [13]. pressure cooker. High-acid fruits like strawberries require
no preservatives to can and only a short boiling cycle,
iii. Vacuum packing: Vacuum-packing stores food in a whereas marginal fruits such as tomatoes require longer
vacuum environment, usually in an air-tight bag or bottle. boiling and addition of other acidic elements. Low acid
The vacuum environment strips bacteria of oxygen needed foods, such as vegetables and meats require pressure
for survival, slowing spoiling. Vacuum-packing is canning. Food preserved by canning or bottling is at
commonly used for storing nuts to reduce loss of flavour immediate risk of spoilage once the can or bottle has been
from oxidation. opened. Lack of quality control in the canning process
may allow ingress of water or micro-organisms. Most
iv. Salt: Salting or curing draws moisture from the meat such failures are rapidly detected as decomposition within
through a process of osmosis. Meat is cured with salt or the can causing gas production and the can will swell or
sugar, or a combination of the two. Nitrates and nitrites burst. However, there have been examples of poor
are also often used to cure meat and contribute the manufacture (underprocessing) and poor hygiene allowing
characteristic pink color, as well as inhibition of contamination of canned food by the obligate anaerobe
Clostridium botulinum. Clostridium botulinum, which produces an acute toxin
within the food, leading to severe illness or death. This
v. Sugar: Sugar is used to preserve fruits, either in syrup organism produces no gas or obvious taste and remains
with fruit such as apples, pears, peaches, apricots, plums undetected by taste or smell. Its toxin is denatured by
or in crystallized form where the preserved material is cooking, though, cooked mushrooms, handled poorly and
cooked in sugar to the point of crystallization and the then canned, can support the growth of Staphylococcus
resultant product is then stored dry. This method is used aureus, which produces a toxin that is not destroyed by
for the skins of citrus fruit (candied peel), angelica and canning or subsequent reheating [15].
ginger. A modification of this process produces glace fruit
such as glace cherries where the fruit is preserved in sugar ix. Jellying: Food may be preserved by cooking in a material
but is then extracted from the syrup and sold, the that solidifies to form a gel. Such materials include
preservation being maintained by the sugar content of the gelatine, agar, maize flour and arrowroot flour. Some
fruit and the superficial coating of syrup. The use of sugar foods naturally form a protein gel when cooked such as
is often combined with alcohol for preservation of luxury eels and elvers, and sipunculid worms which are a
products such as fruit in brandy or other spirits [14]. delicacy in the town of Xiamen in Fujian province of the
People’s Republic of China. Jellied eels are a delicacy in
vi. Pickling: Pickling is a method of preserving food in an the East End of London where they are eaten with mashed
edible anti-microbial liquid. Pickling can be broadly potatoes. Potted meats in aspic, (a gel made from gelatine
categorized as chemical pickling for example, in chemical and clarified meat broth) were a common way of serving
pickling, the food is placed in an edible liquid that inhibits meat off-cuts in the UK until the 1950s. Many jugged
or kills bacteria and other micro-organisms. Typical meats are also jellied. Fruit preserved by jellying is known
pickling agents include brine (high in salt), vinegar, as jelly, marmalade, or fruit preserves. In this case, the
alcohol, and vegetable oil, especially olive oil but also jellying agent is usually pectin, either added during
many other oils. Many chemical pickling processes also cooking or arising naturally from the fruit. Most preserved
involve heating or boiling so that the food being preserved fruit is also sugared in jars. Heating, packaging and acid
becomes saturated with the pickling agent. Common and sugar provide the preservation.
chemically pickled foods include cucumbers, peppers,
corned beef, herring, and eggs, as well mixed vegetables x. Potting: A traditional British way of preserving meat
such as piccalilli. In fermentation pickling, the food itself (particularly shrimp) is by setting it in a pot and sealing it
produces the preservation agent, typically by a process with a layer of fat. Also common is potted chicken liver.
that produces lactic acid. Fermented pickles include
sauerkraut, nukazuke, kimchi, surstromming, and curtido. xi. Jugging: Meat can be preserved by jugging, the process
Some pickled cucumbers are also fermented. of stewing the meat (commonly game or fish) in a covered
Abdulmumeen et al., 2012 39
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